Ignition system



y .20, 19 H. B. eRow 2,324,923

IGNITION SYSTEM Filed March 19, 1942 23 a2 (a as 32 gall -11 2 5 10 4 .4

INVENTOR Harlozufl Gmlu ATTORNEY 1 8 g Patented July 20, 1943 UNITEDLearnt Room STATES PATENT OFFICE Claims.

This invention relates to an ignition system for internal combustionengines, and the means whereby that system is rendered operative.

One of the prime objects of this invention is to provide an ignitionsystem for internal combustion engines which will effectively eliminateelectricinterference with the operation of sensitive instruments andradio devices, especially on board of aircraft.

Another object of this invention is to provide an ignition systemwherein a high potential current is caused to flow continuously throughthe electrodes of an ignition device, such as a spark plug, and whereinsuch continuous high potential current flows through the electrodes ofall spark plugs of an internal combustion engine, while these plugelectrodes are either in contact or are spaced from one another.

Still another object of this invention is to provide an electricallynon-interfering ignition system for internal combustion engines, whereinone of the electrodes of the ignition-producing device employed in thesystem is fixed or stationary, while the other electrode thereof ismovable, and wherein the electrodes are normally urged into contact withone another and conduct a steady fiow of high potential current,irrespective of whether they are in contacting or separated positions,and wherein means are provided for actuating the movable electrode sothat it will momentarily separate from the fixed electrode to form a gapbetween the electrodes for producing an electric arc to effect ignitionof a charge.

Another important object of this invention is to provide a spark plughaving insulated fixed and movable electrodes which are normally incontact with one another, and wherein the movable electrode is normallyurged against the fixed electrode by electro-conductive means, andwherein other electro-conductive means are provided for actuating themovable electrode, both of said electro-conductive means being adaptedto form electro-conductive extensions of the movable electrode, forconducting high potential current from the movable electrode to thefixed electrode.

The foregoing and still further objects and important advantages of thepresent invention will become more fully disclosed in the accompanyingdrawing and the appended specification and explanatory matter, and inwhich drawing:

Fig. 1 is an elevation partially in cross section of a spark plug inaccordance with my invention;

Fig. 2 is a top view of the cover or closure of the sp rk p u Fig. 3 isa vertical cross section therethrough taken on line 3-3 of Fig. 2;

Fig. 4 is a partial front view, and Fig. 5 is a fragmental sideelevation of an insulating member employed within the spark plug; and

Fig. 6 is a diagram indicating a typical ignition system in accordancewith my invention.

Referring first to Figs. 1 to 5, inclusive, numeral [0 denotes a portionof a cylinder of an internal combustion engine, wherein a spark plug IIis secured. The spark plug consists of a metallic base l2 in the generalform of a bushing, and is provided with a central flange l3 adapted tofacilitate the engagement thereof by a wrench, and having two threadedportions extending above and below the flange, and indicatedrespectively at I4 and I5. The base has a tapered seat l6, upon whichrests a correspondingly tapered face of an insulating member H, whichlatter is provided with at least two passages for the reception of afixed or stationary electrode l8 and a movabl electrode I9. The fixedelectrode is preferably cemented in its passage and is shown in thedrawing to be provided with a horizontal leg 20, which forms a rest formovable electrode IS. The upper end of fixed electrode I8 is held withina locking block 2|, through which passes a terminal post 22, the latterserving as fastening means within block 2| for the upper end ofelectrode l8.

It will be observed that insulating member I! has a recess foraccommodating locking block 2|. It will be further noted that the upperend of movable electrode i9 is housed within a cylindrical recessprovided in insulating member IT. The upper end of electrode I9 isprovided with an annular flange 23 against which bears an expansionspring 24. This spring is intended to normally urge electrode I9 intocontact with leg of fixed electrode 18.

Immediately above insulating member I1 there is arranged anelectromagnet 25 which is completely insulated electrically both fromwithin and from without. At the center of the electromagnet is disposeda soft iron core 26, terminating at its upper end in a binding post 21.Spring 24 bears with its upper end against the bottom end of core 26,which latter is electrically insulated from the magnet coil. Core 26 andspring 24 form electro-conductive extensions of movable electrode IS.

The exterior insulation surrounding electromagnet 25 consists of aring-shaped member 28, from which extends downwardly a binding postsupport 29 for the reception of binding post 22, connected to the fixedelectrode l8, and binding posts 30 and 3| forming the termini ofelectromagnet 25. The lower binding post 30 is electrically shieldedfrom binding post 22 by a semicylindrical insulating shield 32,extending from binding post support 29. This support is provided with avertical guide channel 33 (see Fig. 5).

The entire electromagnetic arrangement, including the ring-shapedinsulating member 28, is housed within a metal cover 34. The latter isprovided-with a vertical guide slot for accommodating binding postsupport 29 by way of channel 33. Cover 34 has an annular flange 36 atits bottom, which fiange is adapted to be engaged by the inwardly turnedupper end of a hollow nut 31. The interior thread of nut 31 engagesupper threaded extension l4 of the base, whereby insulating member l1and the electromagnetic arrangement above the insulating member aretightened in position and are held in proper relation to one anotherwithin the base. Thus the entire structure of the spark plug is causedto form a compact unit.

When electromagnet 25 becomes energized, soft iron core 26 becomesmagnetized and attracts movable electrode l9, causing it to moveupwards, against the tension of spring 24. this movement the normallycontacting electrodes become momentarily separated, whereby a gap isformed between them. It is intended that the electrodes serve asconductors for a continuous flow of a high potential current. The gapformed between the separated electrodes will thus produce an electricarc sufiicient to effect ignition of a charge within the cylinder.

The foregoing description of the spark plug is intended for explanatorypurposes only so that the following matter will become more easilyunderstood. It is quite obvious however that the construction of thespark plug illustrated is by no means intended to limit my invention tothe details disclosed and that variation may be resorted to in meetingdifierent requirements.

Referring now to the diagram shown in Fig. 6, numeral 38 indicates a lowpotential source of electric energy, grounded at 39 and connected to adiagrammatically illustrated distributor 48. The latter, for explanatorypurposes, consists of a movable contact member or brush 4|, adapted torotate and to pass alternately over contacts 42 and 43. These contactsand brush4l are preferably bridged by by-pass condensers 44.

The spark plugs, forming part of the system illustrated in Fig. 6, areindicated diagrammatically at 45 and 46. The detail structure of thesespark plugs, as shown in Fig. 1, is omitted and only the major portionsare retained, such as stationary electrodes 41 and 48, movableelectrodes 49 and 50 and solenoids 5| and 52.

It will be seen that brush contact 42 is connected through conductor 53to solenoid 52, while the bottom lead of the solenoid 54 is grounded.Fixed contact point 43 of the distributor is connected by means ofconductor 55 to solenoid 5|, While the other lead 56 from the solenoidis rounded.

At the bottom of the figure a high potential electric source 51 isindicated, from which leads conductor 58 to fixed electrode 41 of sparkplug 45. The c 1rrent passes through fixed electrode 41, to movableelectrode 49, through the core of electroma'gnet 5|, to conductor 59,which connects with fixed electrode 48 of spark plug 46. The currentflows from fixed electrode 48 through movable electrode 50, andcontinues through the core of electromagnet 52, from which it passes bymeans of conductor 60 back to electric source 51. The fiow of highpotential current supplied from source 51 is intended to be continuousand not interrupted at any time. All conductors leading from the sourceto the spark plugs and from one spark plug to another spark plug areintended to be sufliciently insulated to prevent leakage of current.

Timing device 40 is shown to contain only two fixed brush contacts, andsimilarly only two spark plugs are indicated. Obviously the system canbe enlarged to include any number of timing contacts and spark plugs.

The operation of the system is very simple and effective. When brush 4|passes over fixed brush contacts 42 or 43 the electromagnets controlledby the contacts become energized, and when thus energized will causemovable electrodes 50 and 49, normally in contact with fixed electrodes48 and 41, to momentarily separate from the latter electrodes,respectively. Through this momentary separation of the electrodes gapsare formed between them to produce electric arcs, which will ignite thecharge within the cylinders controlled by the respective spark plugs.The fact that the high tension current continuously flows through theelectrodes of the spark plugs is indicated by broken lines passingthrough the centers of the electrodes. There is never an interruption ofthe high potential current flowing through the system including thespark plugs. In consequence of this uninterrupted fiow of current, andthe fact that arcs produced in the gaps of two distanced electrodes areshielded within the metal of the engine cylinders, and, furthermore,since all leads serving the high potential electric source supplied tothe spark plugs are intended to be thoroughly shielded, the shieldingbeing grounded, not shown, electric interference with sensitiveinstruments and especially radios is positively eliminated.

The low potential current flowing through the electromagnets foractuating the movable electrodes of the spark plugs ordinarily will notinterfere with radio reception, especially when points intended formaking and breaking contacts are properly shielded and are provided withcondensers, as indicated at 44.

From the above description it will become quite evident that the presentinvention is intended to provide an effective ignition system forinternal combustion engines, wherein a high potential current commonlyused in such systems is employed to assure positive ignition when andwhere desired, and wherein man-made static interference ordinarilyaccompanying the use of high potential current in an ignition system iseffectively prevented. It will be also evident that the high potentialcurrent employed in the spark plugs is rendered non-interfering in thatit is caused to flow continuously and without interruption through theentire ignition system, irrespective of the fact whether the electrodesof the spark plugs are in their normal, contacting position, or areseparated momentarily for producing arcs for the purpose of effectingignition.

It may be mentioned also that the present system possesses otherinherent advantages over present day spark systems using either sparkplugs with fixed gaps, or ignition devices with mechanical interrupters.In both of these systems either spark coils or magnetos are employed,which produce peaks in current during ignition periods. and the sparksproduced may be termed jumping sparks which comprise exchanges ofelectric charges between the electrodes of the sparking device. In bothtypes of these ignition devices there is present an initial resistancecaused by the surrounding atmosphere, which latter has to be overcome byioniza- Ll. CLE'i if? i UiSUHAKGi'.

tion before a fairly unrestricted exchange of discharges may follow.

It is to be noted that the intensities of the sparks andtheir length inheretofore used ignition devices Will vary with altitude. At sea levelan ignition spark requires greater intensity, and the spark is short.When the device is used at higher altitudes the resistance of thesurrounding atmosphere is lessened and the length of the sparkincreases. This fact is the cause of ignition failures, in that thecurrent intended to pass through the sparking device is diverted byshorts or sparks jumping from conduits to the engine body or otherengine parts.

In the present systemthe above possibilities of defects in ignition areentirely eliminated for the following reasons:

In the first place the current supplying the ignition system is auniform, continuous current without peaks, which flows evenly overconductors which are entirely insulated from all parts of the engine.

Secondly, this system does not produce any sparks in the sense explainedabove, but the so-called sparks produced by the separation of theelectrodes in the present invention constitute portions of aonedirectional, continuous current, although these portions are exposedto induce ignition.

'Ihirdly, since sparks of the type produced in heretofore employedignition systems are nonexistent in the present system, a change inaltitude will have no influence upon and will not affect the properfunctioning of the present device. Consequently shorts by-passing sparkplugs will also be eliminated.

While in the illustrations the movable electrodes are shown to beactuated by employing a non-interfering, low tension current forenergizing electromagnets, it is quite obvious that mechanical devicesfor operating the movable electrodes may be substituted with equallysatisfactory results.

Thus while specific structures and diagrams have been illustrated anddescribed, it is selfevident that my invention shall not be restrictedto the actual disclosures, and I therefore reserve for myself the rightto make changes and improvements in my invention, without departing fromits broad scope, as defined in the annexed claims.

I claim:

1. In an ignition system for internal combustion engines, a closedelectric circuit, a source of electric energy continuously supplyingsaid circuit, an interrupter-type spark plug in said circuit, theelectrodes of said spark plug being normally in contact with each other,and means for momentarily separating the spark plug electrodes whenignition is desired.

2. In an ignition system for internal combustion engines, a continuouslyenergized, closed electric circuit, including a source of electricenergy and an interrupter-type spark plug, having normally contactingelectrodes, adapted to be separated for producing a gap at the momentignition is to take place, and timed means for causing a momentaryseparation of said electrodes.

3. In an ignition system for internal combustion engines, as set forthin claim 2, said spark plug having one fixed and one movable electrode,said timed means for momentarily separating Search Reom said electrodescomprising a mechanism for actuating said movable electrode.

4. In an ignition system for internal combustion engines, as set forthin claim 2, said spark plug having one fixed and one movable electrode,said timed means for momentarily separating said electrodes comprising amechanism for actuating said movable electrode, said mechanismcomprising an electromagnet, another source of energy supplying electriccurrent to the latter, and a timing device controlling the supply ofelectric energy from said other source to said electromagnet.

5. In an ignition system for internal combustion engines, as set forthin claim 2, said spark plug having one fixed and one movable electrode,said timed means for momentarily separating said electrodes comprising amechanism for actuating said movable electrode, said mechanismcomprising an electromagnet, another source of energy supplying electriccurrent to the latter, and a timing device controlling the supply ofelectric energy from said other source to said electromagnet, said firstmentioned source of electric energy being adapted to supply said closedelectric circuit with a high tension current, said other source ofenergy for energizing said electromagnet adapted to supply a low tensioncur rent.

6. In an electric ignition system employing spark-producing means, aclosed, uninterrupted electric circuit including said spark-producingmeans, and carrying a continuous, high potential current, saidspark-producing means being adapted to form a gap for inducing acontinuous electric are when ignition is desired.

7. In a spark plug for producing a non-fluctuating electric ignitionarc, normally contacting fixed and movable electrodes, adapted-to serveas conductors for a constant, continuously fiowing high potentialcurrent, and means for actuating the movable electrode to momentarilyseparate it from the fixed electrode, so that a gap is formed betweenthe electrodes when an ignition are is to be produced.

8. In a spark plug, as set forth in claim 7, said actuating meanscomprising an electromagnetic instrumentality, controlled by a lowpotential electric current, and adapted to attract the movable electrodeto bodily move the latter away from the fixed electrode.

9. In a spark plug structure, a mountable casing consisting of a baseand a detachable cover, an electromagnet and an insulating core fixedlyheld within the casing, passages in the core, fixed and movableelectrodes in the passages, said electromagnet being adapted to attractsaid movable electrode when energized, conductive means between the ironcore of said electromagnet and said movable electrode for normallyurging the latter into contact with said fixed electrode, bothelectrodes being adapted to conduct an uninterrupted current of a highpotential, said electromagnet being energized by a low potential current, said iron core being electrically insulated and serving as acontinuation of the movable electrode.

10. In a spark plug structure, as set forth in claim 9, an insulatingmember engaging and held by said cover, and binding posts for saidelectromagnet and for the fixed electrode supported by said member.

HARLOW B. GROW.

